What's the deal with girls' bikes?

Why are there men's and women's bikes? If the center bar was originally placed to accommodate "ladies wear," then what gives? I saw a newer design this week, and it was not gender specific.

-- P. Granger, San Diego

For the first hundred years or so of bicycling, women were smart enough to avoid the bone-braking, dangerous (wooden!) vehicles. They let men work out the kinks in the machinery. But in the late 1800s, when mechanical and design enhancements made cycling a saner sport, women took to it immediately. "Chief of all the dangers attending this new development of feminine freedom is the intoxication with comes with unfettered freedom," one sourpuss wrote in 1896. Acrobats, performers, and other shady women rode bikes for shock value and attention. Serious women riders and racers wore knickerbockers ("bifurcated nether garments"). But in the late 1890s, when the diamond-shaped tubular bike frame came into wide use, the modesty problem for the average woman recreational rider was solved by the drop-frame bike; the top bar was removed to accommodate ankle-length dresses. This required that the frame be made heavier for strength, and chain guards and rear-wheel dress protectors were added. To further guarantee they'd be adequately covered, women often weighed down their cycling-skirt hems with buckshot. I guess if you buy your kids Ken and Barbie bikes today, one will have a bar, one won't. These days there's no need for two styles, of course, except to keep your kid from being teased on the playground. Designers of serious machines go for strength, lightness, and efficient energy transmission, all unisex qualities.